Automatic-stoker dumping grate



Feb. 16,1926. 7 r 1,572,945

' O. O. NYGAARD AUTOMATIC STOKER DUMPING GRAT E Original F'iiqd June 15, 1918 5 Gets-Sheet 1 Feb.

O. O. NYGAARD AUTOMATIC STOKER DUMPING ,GRATE l5, i9 l8 Feb. 16, 1926.

- O. O; NYGAARD AUTOMATIC STOKER DUMPING GRATE o i i Filed June 15, 19 8 3 Sheets-Sheet 5 (lam/e Q atj Patented Feb. 1%, 1926,

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OSCAR O. NYGAARD. OF BOSTON, MASSACHUSETTS, ASSIGNOR TO COMBUSTION ENGI- NEERING CORPORATION,

015 NEW YORK, N. Y., A CORPORATION OIE NEW YORK.

AUTOMATIC'STOKER DUMIE'ING- GBATE.

Original application filed June 15, 1918, Serial Irt'o. 240,160.

To a7Z whom it may concern:

Be it known that I, OSCAR O. NYGAARD, a citizen of the United States, and a resident of Boston, Massachusetts, whose post-office address is No. 57 Vvestmore Road, Mattapan, Massachusetts, have invented an Improvement in Automatic-Stoker Dumping Grates, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My present invention relates to grates, and more particularly to dumping grates and operating means therefor, for use in automatic stokers. While my improved dumping grate is capable of application to stoking apparatus of practically any commercial type, I have designed itprimarily for use in connection with automatic stoking mechanism of the underfeed type, and the drawings accompanying this specification illustrate it in this connection.

The present application is a division of my application for an automatic stoker, filed June 15, 1918, Serial Number 240,160 issued as Patent No. 1,441,293, dated January 9, 1923, and reissued as No. 15,963, dated December S), 1924. In automatic stokers it is essential for proper and economical operation, that the speed of operation of the dumping grates be capable of being varied within wide limits .in order to efiiciently handle different classes of fuel, as well as to handle the variable load imposed on it by the fuel feeding means, the speed of which may be varied from normal to forced draft load.

A feature of my invention is an improved arrangement of dumping grates and the means for actuating the same. These dumping grates are preferably so positioned, so formed, and so actuated as to effect a constant dumping and rearwardly feeding action on the consumed portions of the fuel,

regulated at a speed in proper timed rela tion with the consumption of the fuel and the actuation of the clinker moving ram. These dumping grates or bars include means to effect a cam-like or eccentric feeding and dumping action under adjustable and automatic control, together with peculiarly Divided and this application filed s in is,

Eicrial No. 289,681.

formed corrugations in the surfaces of the grate bars to facilitate this feeding of the ashes during dumping.

Another feature of my invention is an improved and novel means for counterbalancing the dumpbars, which allows them to be operated with a minimum of power.

A further feature of my invention is the maintaining of the bridge wall free of clinkers, crushing and removing any clinkers formed thereon at the dumping end of the Stoker. This feature is very important as it provides efficient means for preventing the accumulation of spent fuel at the end of the fire box, this accumulation having in they past. been the source of much trouble and expense.

Additional improved features consist in the form and arrangement of the actuating mechanism for the dumping bars, the accessibility of all working parts, and other details of construction and arrangement which will be apparent as the description of the invention progresses, and which will be specifically pointed out in the appended claims.

Referring to the drawings:

Fig, lis a plan view of an automatic underfeed stokert-o which my invention has been applied, only so much of the stoker be-- ing shown and described as to clearly illustrate the use of my improved dumping grates in connection therewith.

Fig. 2 is a longitudinal sectional View through one of the retorts showing one of the dumping grates in side elevation.

Fig. 3 is a side elevation of an automatic stoker, showing in detail the ash feeding and dumping device, and the manner in which the same is adjusted, portions of the furnace wall and structure being broken away to show the relation of said ash feeding and dumping device to the grate structure. I a

Referring tothe drawings, and particularly to Figs. 1 and 2, which show a stoker as a working unit comprising three retorts; the floor or foundation 1, preferably of concrete, and front wall 2, usually of brick, are designed in conventional form, the

cross beam 3 spanning the opening for the 'verse support consists in a pair of I-beams 4 imbedded in the floor or foundation 1, on which rests a flange or foot 5 of the inner end of the sides 6, 6, forming each" retort.

These sides are preferably of cast iron, with a slight upward flare to prevent the coal sticking during coking, and form the troughs or retorts 7 to receive the coal supply'and have on the outer sides a plurality of lugs 8, 8, on which the tuyere boxes rest. Each side has a depending web 9 on which the flange 5 is'carried at the bottom, and a rearwardly extendingbracket 10, having therein a recess 11 to support the overfeed grates, as will be described, a vertical brace or web 12 holding each pair of sides 6 in a retort together at the rearward or grate end, while the relatively heavy flange. 13

at the front end, which is bolted to the I-beam 3, supports the front of each retort.

Preferably the sides 6', webs 9, 10, 12, flange- 13 and trough bottoms 14 and 15, and cap or cover 16, are all formed as a single casting, providing a passageway for the .fuel

from the opening 17 into the trough 7, and a corresponding opening 18 for the clinker pusher, these openings being preferably square to receive squared rams or pushers 105 therein, the upper portion 14 being extended over the opening 18 as shown at 19 to provide a bearing for said second pusher I 105. This second pusher 105 positioned for fuel and clinker feeding, within the furnace, constitutes the means for leveling and shaping the fuel bed, as well as for feeding the refuse formed at the lower end of each retort, over the Qverfeed grates and onto the refuse depository positioned at the lower and rearmost end of the furnace. I provide these lower pushers or' rams with independent adjustable driving means, and with air ports in the fuel supporting surface of said pushers to add active grate surface,as is more fully explained in my copending application for automatic stoker, Ser. No. 240,160, filed June 15, 1918 issued as Patent No. 1,441,293 dated January 9, 1923, and reissued as No. 15,963, dated December 9, 1924.

It will be understood, from an examination of the drawings, that theselower fuel and clinker feeding and grate actuating means within the furnace, are capable of adjusting the fuel bed asto shape or form.

.floor 26 inclined at the forward and cooperates with these pushers in cleanments, at the will of the operator, independently of both the grate actuating means, and the means that feed the fuel into the furmice, and is adjustable, at the will of the operator, both as to the amount of angular tilt, and the amount of oscillatory movement imparted to said dumping grates.

It is highly desirable in a dumping grate to combine all these independent adjustments and movements, in that it gives greater flexibility to the stoker, to take care of a greater variety of coal and load conditions, and it means a dumping grate capable of a greater variety of adjustments, and consequently of greatercapacity for automatically removing the refuse from the furnace, than any one device at the present in use and'known to applicant. Across the rear portion of the bottom 15 is a flange 20, to which is bolted an extension 21 of the bottom of the trough 7 which extension has a circularrecess 22, and a further part 23 constituting a cover or top across the brackets 10. At the front or receiving end of each retort, is affixed a hollow casting 24 to con-' stitute a bearing for'the fuel feeding ram 25 in eachr etort, said casting having its portion as shown at 26, resting on the top of the I-beam 3 and constituting alcontinuous bottom with the portion 14 of the trough 7, through which the fuel is. forced, Each casting 24 has the inner side walls flared slightly, as shown at 27, 27, opening upwardly into'the funnel parts 28, 28, connecting with the coal receiving chute 29 on top of the ram 25 and fastened onto the casting 24 is a scraper 30.

The casting 24 is provided with a flange 35-which is secured by bolts 36, 36, to a suitable support 37 carrying the bearings 38 of the crankshaft 40, arranged tooperate said rams 25, connecting rods 41 being each suitably pivoted to said crankshaft between bearings 38, at one end, and with the other end pivoted to the crossbar 42 ineach ram.

Formed on the topof each trough is a connecting cover 16, preferably formed hollow to receive a portion of the air supply and keep the same cool, preventing it from burning out. This cover 16 is fitted closely underneath the front. wall 2, and with :i-

small forward section 16 removable, and renewable, this being the only portion of this cover 16 which is apt to wear out or burn out, as it is that part exposed to the intense heat of the fires on the stoker. Each cover 16 is preferably shaped as a hollow box having an air receiving inlet 39 and a downwardly directed outlet 39, this outlet being formed as a slit or opening between the upper portion of the cover 16 and the removable section 16, thus providing a constant current of air through the cover 16 .and in front of the removable section 16,

directly into the fuel bed, such fuel bed taking approximately the shape indicated by the dotted line 44; in Fig. I

Between the troughs and therefore between the adjacent sides 6 forming the troughs, and resting on the lugs 8, are positioned my novel type of tuyere boxes, but since they form no part of the present in vention, they will not be described in detail, being described and claimed in my Reissue Patent No. 15,963, dated Dec. 9, 19%. of which the present application is a division. In my improved stoker, I have combined with theretorts and underfeed features, an overfeed grate 71 interposed between the underfeed grates and the dumping devices, which overfeed grate is positioned at a sharper angle than the incline on which the tuyeres and retorts are built, this arrangement facilitating the feeding of the nearly consumed fuel and ashes which reach this point. The overfeed grate 71 is supported at the forward end on the transversely positioned bar 77 in the recess 11 in the bracket 10, and at the lower and rearmost end on the upstanding rim of a plate 80 secured to a transversely positioned channel beam 81. The web 12.at the rear of each retort has an opening therethrough as shown at 70, Fig. 2, permitting the air from the large chamber to pass therethrough and supply the over-feed grate 71. The damper. 79 mounted on a rockshaft 73 is controlled by a handle 7% outside the stoker. This rockshaft 78 runs transversely through the webs or legs 9 at the rear of each retort, thus making it possible to control the air passing through all the openings simultaneously. My arrangement of dumping sections, which are preferably operated automatically and continuously, although they may be freely actuated by hand or disconnected from the automatic actuation, consists in very simple and etlicient devices.

The grate sections are preferably in alignment with the overfeed grates 71, and are mounted on the shaft 85, which shaft is se-- cured in suitable bearings 86 at a plurality of points transversely of the stolter by brackets 87 having flanges 88, bolted to the channel beam 81 and support 80.

Each dump grate section is preferably mounted on a supporting web 90, which is of a eam'like shape and secured to the shaft 85. The offset portion 90 of the web 90 together with the grate section forms the fuel and refuse supporting surface. The web 90 secured to shaft 85, and the grate section 95, are normally supported for automatic operation in a tilted position, so that upon movement being imparted to the shaft 85, the ofset portion 90 of the web 90 and the upper surface of the grate section 95 will move principally in a rearward direction, whereas the lower end of the grate section 95 will move in a downward and forward direction.

Fromthis it will be seen that with the teeth 98, a fuel and refuse supporting surface capable of a positive rearwardly feed ing action, as well as a downwardly and forwardly dumping action is provided, the proportion of the rearwardly feeding action beingpreferably as one to three of the downwardly and forwardly dumping action. However, I do not wish to be limited to the exact proportions stated, as it is possible to vary the proportion without departing from'the spirit of the invention. v

Passing through the rearward end of the web 90 is a bar 182 (see Fig. 2) andthis bar tends to hold the webs 90 and sections 9 95 in line, and also tends to distribute the strain imposed on one grate section to a number of sections when crushing clinkers. As the webs-90 and the grates thereon extend at oneside of-the shaft 85, I apply a hanger 91 keyed to each end of the shaft 85 and con-. n ct said hangers by a rod 92, on which rod are many counterbalancing weights 92*, in order to effectually counterbalance the dumping sections, and thus render the os-= cillat ion of the shaft 85 relatively easy, and requiring but a small amount'of power. The grate sections 95 are adapted to straddle each support 90, a pair of depending lugs 96, 96, extending downwardly on the underneath side of each section to engage the supporting web 90, and be secured thereto by a cotter pin 97' and bolt 197respective- 1y. I prefer to form these dumping sections 95 with a plurality of teeth running hori- Zontally and designated at 98, said teeth having slanting upper surfaces and relatively perpendicular lower faces 99. This facilitates the feeding action on the refuse resting on these grates-as the shaft 85 is rocked, because of the formation of these teeth and the movement of the dumping section toward the extreme rear or discharge point 100 at the end of the dump bars. The discharge point is preferably reinforced by an extra heavy bar so as to prevent undue wear at this point and furthermore enable the rocking of the dump sections to crush, pulverize, and loosen the ashes between the dump sections and the bridge wall of the connected with the independent driving mechanism provided for the lower fuel feeding and clinker pushing rams of the stoker, so that the shaft 85 may be oscillated when the upper fuel feeding rams are at a stand? still, thereby making the stoker more selfcleaning in its action.

The position of said 'gra-tes'during oscillation may be adjusted by fitting one of the pinsl02 in a selected one of said plurality of slots in rod 103, so that the dump grates may be adjusted in a more or less vertical position and consequently with a greater or lesseropening between the bridge wall andthe dumping end of the grates at the start of its oscillation,also the stroke or oscillation of said-grates during full turn of driving shaft may-be adjusted to meet any requirements by fitting the rod 103 to a selected one of the pins 102, thereby adjusting the discharge of ashes proportionate to the feeding in and consumption of fuel.

From the foregoing it will be understood that a very important feature of my dumping grate and novel driving connections lies in the wide adjustability, ease and facility with which the operation of said grate can be-instantly changed to meet any demand made upon it in the change of load or fuel, and I want to strongly emphasize the importance of "this arrangement which arrangement I want to claim broadly.

The operation of my invention is as follows:

It is assumed that the fuel is being continually pushed into the combustion chamber, where it is gradually consumed, the burning process going on as the fuel moves over the 'overfeed grates '71 and onto the dumping grates 951 During this operation, the various mechanisms described above and illustrated in the drawings, are being driven from suitable driving mechanism, and it now becomes necessary to operate the dumping grates automatically and in accordance with the speed'with which the fuel is being fed and consumed. The connecting rod 103 is therefore set on the pin 102, securing an automatic rocking and'on' account of the 'eccentrically mounted grate surface with respect to the shaft 85, consequently a feeding and dumping action on the ashes deposited thereon. I prefer to have the conand the-line of the brid e wall Y feeding of the clinkers,

necting rod 103 actuated in cooperative relation with the clinker pushers and therefore eonnectthe rod 103 by its eccentric strap 180 on an eccentric keyed to the outer end of the shaft 123 actuating the clinker pushers; This arrangement permits the dumping grates to be set for any degree of opening between the rearmost portion 100 L: cated" approximately in Fig. 2.

By having the overfeed grate sections at a steeper inclination than the line of the retorts and tuyere boxes, I secure a positive ashes and consuming fuel directly onto the dumping sections as rapidly as desired without the necessity of moving, reciprocating and oscillating the overfeed section of my stoker, while the large air spaces therein afford means to complete the burning of all remaining combustible material in the fuel at this oint.

While I have described the pref drred embodiment of my invention, it will be understood that minor changes in the details of construction and arrangement of parts may be made within the scope of the appended claims without departing from the spirit of the invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is y 1. In a furnace, a' rockshaft, automatic and adjustable moving means forthe rock- 181 as indishaft, a plurality of grate members mounted on said rockshaft, a renewable refuse supporting surface mounted on each of said grate members and forming one boundary of a refusedischarge opening, a wall located opposite said supporting surfaces and forming another boundary for said opening,

said refuse supporting surfaces positioned with a part thereof near the wall and with another part thereof more remote from said wall, said automatic and adjustable moving means for the rockshaft constituting means for simultaneously moving the part of said supporting surfaces more remote from the wall toward, and the part of said surfaces near the wall away from, said wall and means to equalize the strain on said grate members. v

2. In a furnace, a fuel supporting surface, a wall bounding one side of a refuse discharge opening, a dumping-grate comprising a rockshaft, a plurality of grate members mounted on said rockshaft, said gratepositioned at an inc-line upwardly from said wall toward said fuel supporting surface and forming when in one position a closure for said refuse discharge opening, automatic and adjustable moving means'for the rockshaft and grate, said means operating to move the part of said grate nearest the wall downwardly and away from said wall at the same time as the refuse supported on the grate is fed toward said wall, and means to connect said grate members together to equalize the strain on said grates.

In a furnace, a roekshaft, a rear wall, a fuel and refuse supporting surface positioned eccentrically of the roclrshaft and attached thereto, said fuel and refuse supporting surface being spaced from said wall and defining, with said wall, a discharge opening, said surface having a portion thereof adjacent to the lower end of said opening, and another portion more remote from said opening, and driving means for said rockshaft, said driving means including adjustable devices for regulating the position of said fuel and refuse supporting surface with respect to said wall, whereby the portion of said surface more remote from the wall will move toward said wallprincipally in a horizontal direction, while the portion near said wall will move away from the wall, whereby said opening will be enlarged and the said portion near thewall will move in a downward direction to facilitate feeding of the refuse down and out through said opening l. in a furnace, a wall, a dumping grate comprising a rockshaft, a plurality of fuel and refuse supporting surfaces mounted eccentrically of the shaft and secured thereto and defining, with said wall, a discharge opening adjacent to one end of the surfaces, and automatic moving means forsaid surfaces, including means for adjusting the angular tilt of the surfaces, in combination with means to adjust the rocking movement imparted to said surfaces, said surfaces being provided with teeth for causing a feeding action on the refuse deposited thereon toward the discharge opening, the discharge opening being enlarged at the same time as the refuse is fed toward said opening.

5. Dumping grate for automatic stokers and driving meanstherefor consisting in a 'roclrshaft, a plurality of grate member's mounted on said rockshaft, counterbalancing means for said members, a furnace wall, said grate members being located in front of a furnace wall and said members positioned at an angle upwardly from said wall, the rearmo-st portion of said grate adapted to vibrate to and from said wall, whereby to crush the clinkers accumulated on the dump ing grate in its movement toward said wall, and to dump the crushed clinkers and other refuse in its movement away from the wall,

a tie rod through the rearmost portion of said grate members to equalize the strain on said grate when crushing clinl-:ers, an arm on said rockshaft to Vibrate said grate, a plurality of connecting means on said arm, said connecting means located at diflerent distances from the center around which the arm vibrates, for adjusting the amount of vibration of said arm and grate, a connecting rod for driving said arm and grate, and

means thereon for adjustahly connecting the same to said arm, to adjust said grate to operate at a greater or lesser tilt or angle with respect to the said wall.

6. Dumping grate and driving means therefor, comprising arockshaft, a plurality of grate members attached thereto, a crank for the rockshaft, a plurality of pins on said crank for adjusting the amount of rocking movement of said grate, and a connecting rod having a plurality of notches adapted for engagement with said pins for adjusting the angular. tilt of said grate members.

7. Dumping grate and driving means therefor, comprising a shaft, a fuel and refuse supporting surface attached thereto, an arm on the shaft, a pluralityof connecting means on. said arm for adjusting the amount of movement of said shaft and surface, a driving rod for said arm, and means on the rod for adjustably connecting said rod to said arm to regulate the angular tilt of said fuel and refuse supporting surface.

8. Dumping grate for automatic stokers and driving means therefor, including a wall, a rockshaft, a fuel and refuse supporting surface attached thereto and co-operat ing with said wall, said surface defining with said wall, a refuse discharge opening, said driving means including adjustable and independent connecting means for regulating the extent of movement of said grate, and the relative position of said grate with respect to said wall.

9. In a stoker furnace having fuel feeding and grate actuating means, an automatic rocking dumpinggrate for use therein, a wall, said dumping grate and wall defining a refuse discharge opening at one end of the grate, and means for adjusting the amount of rocking motion, the angular tilt of said dumping grate, and the size of the refuse discharge opening, without alteration of the amount of movement or speed of the fuel feeding or grate actuating means in the Stoker when making such adjustments.

10. In a stoker furnace of the kind described having grate actuating means and a refuse discharge opening, means to feed fuel into the furnace, an automatic rocking dumping grate for use therewith located immediately adjacent to said refuse dis charge opening, connecting means for transmitting motion from the said means to the dumping grate, said connecting means being adjustable to change the extent of movement of the dumping grate independently of the means for feeding fuel to the furnace, said connecting means including means for regulating the operative position of said grate with respect to the refuse discharge opening.

11. A dumping therefor having, in combination, a Wall, a

grate and driving means I rockshaft, a plurality of refuse supporting members attached thereto'and co-operating With the Wall, said Wall and refuse supporting members defining a discharge opening 5 adjacent to the rear ends of said refuse supporting members, automatic moving means forsaid members, including means for adjusting the tilting position of said members,

and means to adjust the amount of movement imparted to'said members, saidmembers including means to feedthe refuse over said members toward the discharge opening.

In testimony whereof, I have signed my name to this specification.

OSCAR o. NYGAARD. 

